Metal tube sizing apparatus



11, 1964 V o. E. HERMANNs A 3,143,989

METAL TUBE SIZING APPARATUS Filed Aug. 4, 1961 I IN VEN TOR. O TTO E. HERMANNS FIG'I AT TY.

United States Patent 3,143,989 I METAL TUBE SIZING APPARATUS Otto E. Hermanns, Akron, Ohio, assignor to The B. F. Goodrich Company, New York, N.Y., a corporation of New York Filed Aug. 4, 1961, 'Ser. No. 129,355 Claims. (Cl. 113-44) This invention relates to the manufacture of thin Walled tubing, and, more specifically, to the manufacture of thin walled tubing by drawing commercially available tubing of greater than desired wall thickness in a seamless die without reducing its outside diameter.

In the production of items such as metallic bellows for miniature pressure switches .for instance, it is necessary that the tubing from which the bellows are formed be of extremely light gauge, on the order of .003 inch. Tubing of this gauge is not commercially available from stock, and when ordered, it must be made in a special run resulting in delays and prohibitively high costs. This is accentuated due to the fact that the quantity of this tubing needed at any given time is relatively small, on the 'order of a few feet, when compared with the normally large production runs of literally miles of commercial tubing. In addition, the tubing which is obtained is more often than not inherently weak due to having been drawn in a 'split .die. When such a die is used, the lines along which thediesegments are mated cause longitudinal striations in the tubing drawn therein due to minute separation of the segments under the high stresses developed during drawing operations. These striations create stress lines in the finished .tubing such that when the tubing is fabricated into an article which is subjected to the periodic application of forces the tubing tends to crack along these striations.

An objectof this invention is, therefore, the provision of'a method for producing the thin-walled tubing without harmful striations, and insuch a manner that short production runs are economically feasible.

Another'object of this invention is to provide a method for producing'thin-walled tubing from commercially available tubing of greater wall thickness by drawing the latter in a unitary-die without :alteration'of the external diameter of the tubing.

It -is another object of this invention to provide a method of drawing metallic tubing wherein said tubing is ;placed in a unitary drawing-die, gripped at one end and subjected to drawing forces exerted by passing therethrough a 'to'olof slightly larger diameter than that of the inside diameter of said tubing.

It is a further object of this invention to provide a method of progressively drawing metallic tubing wherein said tubing is :placed in a unitary drawing die having a removable tube gripping cap and subjected to drawing forces exerted by passing a plurality of spherical balls through said tubing,'each ball being of a larger diameter than-the inside diameter of the tubing at the time prior to its passage therethrough.

It is a still further object of this invention to provide an'apparatus for carrying out the methods as defined in the preceding paragraphs wherein means are provided to remove the tubing from the die without damage to the readily apparent to those skilled 'in art to which it pertains from the detailed description of a preferred embodiment of the apparatus, suitable for carrying out the method of the invention, described with reference to the appended drawings forming part of this application in which:

FIG. 1 is a front elevational view of the apparatus showing the tube and the tool ram positions at the start of the drawing operation; and

FIG. 2 is a side elevational view, partially 'in section, showing the condition of the apparatus'as the last drawing ball drops from thelower end of the tubing.

The apparatus 10 basically comprises a unitary tubing die 11 removably held on a horizontal workplatform 12. The die 11 has a bore therethrough in which the tube '13 to be drawn is positioned. The drawing is performed, as hereafter described, by forcing a series of balls 14, preferably of hardened steel, which are of gradually increased diameter in the order of their use, through the bore of the tube 13 by means of an axially movable ram rod 15.

The apparatus 10 comprises a main vertical support member 16 from which the horizontal work platform 12 projects. Two vertical side supports 17 serve to stabilize the apparatus 10 and further support the platform 12. The lower portions-of the member 16 and the supports 17 have been cut away in the drawings since-the details thereof are not essential to the invention. Centrally located in the platform 12 is a vertical opening 18 having a diameter slightly greater than the outside diameter of the largest tube 13 to be drawn. On the work platform 12 a ring-shaped die holder 19 is attached, preferably by welding, the holder being axially aligned with the ram rod 15 and the opening 18. The die 11 is supported by platform 12 and located in the die holder 19, being held therein by means of set screws 20. The die 11 has a vertical cylindrical passageway'21 formed therethrough for receiving the tube 13, such passageway 21 being continuous as opposed to a sectionalized passageway formed by separate sections, wherein each section has a semicircular trough. The tube is gripped at its upper end by means of a cap plate 22 having a central opening 23 into which the tubing is flared, as at 24, prior 'to insertion in the die 11. The cap plate 22 also has a downward projecting peripheral flange 25 to locate it on the die 11.

Mounted between cantilever brackets 26 projecting from the upper portion of the front of support member 16 is a double acting hydraulic cylinder 27 containing a piston 28 from which depends a piston 'rod 29 axially aligned with the die passageway 21. At the lower end of the piston rod 29 is mounted a chuck 30 having a circular flange 31. The ram rod 15 is held by the chuck 30 for vertical movement to and from complete penetration of the die passageway 21. Also mounted on the front of support member 16 by means of brackets 32 and 33 are a pair of slide rods 34. Slideably mounted on rods 34 by means of slide guides 35 is a retractor plate 36 having an upper yoke 37 engageable with the flange 31 of chuck 30 and a lower retractor yoke 38 for engagement with thecap plate 25. The apparatus will be more completely understood and appreciated from the following description of the method and operating procedure for-drawing tubing therewith.

Operating Procedure The operator inserts an end of the tube 13, which he has first bevelled in the order of 45 degrees, into the opening 23 of cap plate 22 and flares it against the plate 22, as at 24, by means of a conventionaltube flaring tool, not shown. This may be accomplishedeither while the cap plate 22 is in place ondie 11 or while the cap plate is removed. In either event, thetube 13 must be inserted in the die opening 21, the inside diameter of which is on the order of the outside diameter of the tube 13, and the cap plate 22 located on the upper end of the die ll by means of its flange 25. The operator then selects a ball 14 having the same nominal diameter as that of the inside diameter of the tube 13. This ball '14 is placed at the upper end of the tube 13. Due to minor irregularities in commercial tubing the ball 14 will ordinarily not fall through. The operator then actuates the hydraulic cylinder 27 by rrieans'of manual controls, not shown, to force ram rod 15 downward the full extent of its stroke as seen in full line in FIG. 2. During its stroke the ram rod 15, which is of greater length than that of the die 11, forces the ball 14 through the tube 13 to smooth out the aforementioned irregularities and to seat the outer surface of the tube 13 against the wall of the die 11. The ball 14 drops into a keeper trough 39 mounted on the under side of platform 12 cooperating communication with opening 18. The operator then' actuates the cylinder 27 to raise the ram rod 15 a portion if its vertical stroke to the position shown in FIG. 1. The operator then selects another ball 14 having a diameter preferably .0005 inch larger than the preceding ball, and forces it through the tube 13 in the same manner. He repeats this operation using a slightly larger ball each time until the tube wall has been reduced to the desired thickness. For example, should the opera tor start with tubing having an inside diameter of .488 inch and a wall thickness of .006 inch which he desires to reduce to .003 inch wall thickness, in addition to the first ball having a diameter of .488 inch, he will preferably use twelve balls, each increased in diameter by .0005 inch "over that of the preceding ball. It will be appreciated that in order to prevent damaging deformation of'the balls 14 they should be made of a material having a hardness greater'than that of the tube 13 being drawn.

After the last ball 14 has been forced through the 3. An apparatus for drawing thin-walled preformed cylindrical tubing comprising a frame, a work platform mounted on said frame, a unitary die having a tube receiving continuous passageway formed therethrough mounted on said platform, a cover plate having a tube supporting opening formed therethrough, means to locate said plate on said die such that said opening is in axial alignment with said passageway, a tool for drawing engagement with the inner surface of a tube supported by said opening of said plate and said passageway of said die, fluid pressure means operative to force said tool axially through said tube retained in said opening and said passageway, and

' means to retract said plate and tube gripped thereby from located therein, means on said plate to locate'said plate tube 13, the operator actuates the cylinder 27 to raise the ram rod 15 its full upward stroke to its position as shown in phantom in FIG. 2. During this stroke the flange 31 of the chuck 30 engages the yoke 37 thereby raising retractor plate 36 and the retractor yoke 38. As retractor yoke 38 is raised it engages cap plate 22raising it also to its position shown in phantom in FIG. 2, and thus removing the tube 13 from the die 11 without damage to tube or die. The tube 13 is then removed from the cap plate 22 by the operator by rocking it slightly in the cap plate opening 23, and the small flared portion 24 is trimmed from the tubing.

It will be apparent to those skilled in the art to which this application pertains that changes and modifications may be made in the preferred embodiment of the invention as disclosed herein within the scope of the appended claims.

I claim:

1. An apparatus for drawing thin walled cylindrical metallic tubing, comprising a unitary die having a cylindrical uninterrupted passageway for supporting said tubing, means mounting said die on said apparatus, a tube drawing tool engageable with the inner surface of tubing supported in said die, means to force the tool through said tubing, and tube withdrawing means movable relative to said die and cooperable therewith to retract the drawn tubing from said die.

2. An apparatus for drawing'preformed thin-walled cylindrical metallic tubing, comprising a unitary die having a continuous smooth tube receiving passageway formed therethrough, a plate having a tube opening formed therethrough, means locating said plate on said die with the opening in said plate aligned with said passageway in said die, a tube drawing tool, means to force said tool axially through said aligned passageway and opening with such tube while contained by said die and plate, and means to separate said plate from said die to withdraw the tube from said die.

on said die at one end of said passageway such that said opening is coaxial with said passageway, a drawing tool for engagement with the inner surface ofa tube held by said plate and die, fluid pressure means provided with an axially movable portion engageable with said tool, and means responsive to predetermined movement of said axially movable portion away from said die to remove said plate and tube gripped thereby from said die.

5. An apparatus for reducing the wall gauge of a thin-walled cylindrical metal tube, comprising means to hold said tube by one end thereof, unitary restraining means to prevent a change in the outside diameter of said tube as its wall gauge is reduced, a drawing tool insertable in the tube to be drawn, hydraulic means operative to force said tool through the bore of said tube so restrained, and means to withdraw said holding means and such tube from said restraining means following passage of said tool through said tube in response to predetermined additional movement of said hydraulic means.

6. An apparatus as defined in claim 5, wherein said tool comprises a sphere having a diameter greater than that of the bore diameter of the tube.

7. An apparatus as defined in claim 5, wherein said tool comprises a sphere of material having a hardness greater than that of the'material comprisingsaid tube.

8. The method of reducing the wall gauge of thin- Walled cylindrical metal tubing while maintaining the original outside diameter thereof, comprising the steps of bevelling one end of said tube, striking said tube through an opening in a plate to the extent that said end protrudes slightly from said opening, flaring said end against the sides of opening and against the face of said plate adjacent said end, locating the other end of said tube in the bore of a unitary die such that said plate abuts one end of said die, forcing at least one drawing tool axially through the inside of said tube, withdrawing said tube and plate from said die, and withdrawing said tube from said plate.

9. The method of reducing the wall gauge of a thinwalled cylindrical metal tube while maintaining the original outside diameter thereof, comprising the steps of bevelling one end of said tube, striking said bevelled end through an opening in a supporting plate, flaring said end against the sides of said opening and against the face of said plate adjacent said end, sliding the other end of said tube into the bore of a die having a continuous bore, until said plate abuts against one end of said die, sequentially forcing a plurality of spherical drawing balls having incrementally increased diameters in the order of their use axially through said supported'tube, retracting said plate and tubing from said die, and removing said tubing from said plate.

10. The method of uniformly reducing the wall gauge cal balls having incrementally increased diameters in the 10 order of their use axially through said tube, and moving said member axially away from said die to remove said tube from the latter.

References Cited in the file of this patent UNITED STATES PATENTS Zimmerman June 28, 1932 Jayne Oct. 11, 1938 Norris May 29, 1945 Teachout May 29, 1945 Lynall Jan. 22, 1953 Yowell et al Feb. 20, 1962 Lyon Feb. 27, 1962 FOREIGN PATENTS France Jan. 31, 1950 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION August ll 1964 Patent No, 3 l43 989 Otto E. Hermanns it is hereby certified that error appears in the above numbered petent requiring correction and that the said Letters Patent should read as corrected below.

Column 3 line 21, for "if" read of column 4, line 55 after "of" first occurrence insert said Signed and sealed this 19th dayof Januaryl95a (SEAL) Attest:

EDWARD J. BRENNER ERNEST w. SWIDER' Commissioner of Patents Attesting Officer 

1. AN APPARATUS FOR DRAWING THIN WALLED CYLINDRICAL METALLIC TUBING, COMPRISING A UNITARY DIE HAVING A CYLINDRICAL UNINTERRUPTED PASSAGEWAY FOR SUPPORTING SAID TUBING, MEANS MOUNTING SAID DIE ON SAID APPARATUS, A TUBE DRAWING TOOL ENGAGEABLE WITH THE INNER SURFACE OF TUBING SUPPORTED IN SAID DIE, MEANS TO FORCE THE TOOL THROUGH SAID TUBING, AND TUBE WITHDRAWING MEANS MOVABLE RELATIVE TO SAID DIE AND COOPERABLE THEREWITH TO RETRACT THE DRAWN TUBING FROM SAID DIE. 